This might be a no brainer and one that you might have not really wanted to address with your lover.  Medication can really put a downer in the bedroom for marriages and affairs.  Many different kinds of medications have a lot of side effects and in a lot sexual side effects run high.  No way is anyone saying don’t take your medication because it can cause a decreased sexual desire or will hinder what I feel and how I perform.  Just be aware of what those are and don’t be afraid  to talk to your physician about any problems you are experiencing. Its better to find out the main cause instead of blaming yourself.  And in some cases there are meds out there that can help increase all of the above.  So talk about your sex life with you doctor and you never know how much better it can be.